Today let's talk about skyscrapers. The University
of Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.

Skyscraper is a nice word.
When I was a child, the 41-story 1st National Bank
building loomed larger than anything else in St.
Paul, Minnesota, and it did indeed seem to scrape
the very sky.

The modern skyscraper came into its own in the
early 1890's. But so much new technology had to be
combined before it made sense to raise buildings
beyond about five stories. Before architects could
take that bold step into the sky, someone had to
develop a workable elevator. Someone else had to
see that the shell of the building should be hung
on a steel skeleton -- it wasn't enough to hang
iron facades on wood or brick frames. A whole new
technology of building foundations had to be
invented. People had to learn to design against
wind loads that were becoming enormous.

Architect Tom Peters thinks that the great Chicago
fire of 1871 did a lot to give these lovely
monsters their present shape and form. Before the
fire, Chicago's architecture was uninhibited and
undisciplined. The 18,000 buildings that perished
were made of wood and brick, with some iron facing.
The commerce that'd built Chicago was hardly
touched by the fire, and those interests exerted
great pressure to rebuild a fireproof city -- an
iron city -- and to make the best use of crowded
downtown real estate.

So two factions converged on the rubble -- the
freewheeling builders of old Chicago, and a new
breed of formal designers trained in analytical
mechanics. They didn't agree, but out of their
conflict emerged bold new concepts for making tall
steel-framed buildings -- concepts that had to be
grounded on complex engineering analysis.

These new buildings couldn't rise any higher than
an elevator could carry their occupants. Hydraulic
lifts had been around since the 1830's, but they
couldn't go to great heights. And Elisha Otis
invented a safe steam-powered elevator in 1857. Of
course, it had to have someone stoking a fire under
the boiler. But electric motors finally got around
these problems. The first electric elevators were
tried out in Germany in 1880, and practical control
systems made them effective in the early 1890's.

By the turn of the century the tall buildings were
typically fifteen stories high. 30 years later, the
Empire State building was seven times that. And a
great impetus for all this was Mrs. O'Leary's fictional cow, who
had kicked over her fictional lantern and burned
down a very real Chicago. What followed was a
remarkable convergence of new technologies that
altered American life.

I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.

(Theme music)

Peters, T. F., The Rise of the Skyscraper from the
Ashes of Chicago. American Heritage of Invention
& Technology, Fall 1987, pp. 14-23.